Microstructure and properties of bilayered B 4 C-based composites prepared by hot-pressing

Bilayered B 4 C-based composites were prepared by hot -pressing method. One layer was a B 4 C ceramic layer using C and Ti powders as sintering assistants. The other layer was a B 4 C ductile layer named as BST layer, in which TiC, Si and Ti mixed powders were added to synthesize Ti 3 SiC 2 phase to improve toughness of B 4 C. Although XRD results showed that no Ti 3 SiC 2 was found in the BST layer, SEM and EDS analyses proved that trace amount of lamellar Ti 3 SiC 2 structure was observed under high magnification fractographs in the BST layers with additive contents ( x ) equal to 30 and 40 wt%. Both the flexural strength and fracture toughness of the bilayered B 4 C-based composite increased with the increase in the amount of additions in the BST layer, reaching optimum values of 550 MPa and 6.6 MPa m 1/2 at x = 40 wt%, respectively.